Berkshire's reinsurance operations include Berkshire Hathaway
Reinsurance and General Re.

Reinsurers provide insurance for insurance companies.

Berkshire also owns the primary insurer Geico, and in 2014 $41.3
billion of Berkshire's roughly $195 billion in revenue came from
insurance premiums earned, and the FT notes that 27% of
Berkshire's net earnings in 2014 came from underwriting and
investment profits.

In his latest
letter to shareholders, Berkshire CEO Warren Buffett wrote
that the insurance industry had "been the engine that has
propelled our expansion since 1967."

The FT notes that the Financial Stability Board has named nine
primary insurers including, MetLife, Prudential, and AIG
"systemically important financial institutions," or SIFIs, which
potentially subjects these organizations to further regulation
and capital requirements because of their importance in the event
of a financial crisis.